In the field of automotive engineering, numerous devices are known which are intended to absorb, that is to say accommodate, energy that is generated in the event of a vehicle collision. Such devices are also referred to as “crash boxes”. Crash boxes are arranged for example between the bumpers and the longitudinal members of a vehicle. Up to a certain collision speed, all of the energy can be absorbed by the crash box. This has the advantage that, up to said collision speed, only the crash box is damaged, whereas expensive damage to further components, for example a deformation of the longitudinal member, is prevented. After an accident, it is then merely necessary for the crash box to be exchanged. The demand for easily and cheaply exchangeable crash boxes is based inter alia on cheaper vehicle insurance categories.
A device, which can be regarded as a crash box, for absorbing energy is known for example from DE 41 28 768 A1. The “crash box” presented in said document is illustrated in FIGS. 1A and 1B. A disadvantage of the described crash box is its characteristic that the maximum amount of energy that can be absorbed is constant, and cannot be changed. This has the disadvantage that the crash box cannot be used universally. Rather, for different vehicle types, it is necessary, owing to their different dimensions and their different vehicle masses, to also design and use different crash boxes which are adapted to the respective amount of energy that must be absorbed.
U.S. Pat. No. 3,694,019 A has disclosed a device in which the amount of energy to be absorbed in the event of a collision can be adjusted. For this purpose, it is proposed that the energy be absorbed through the plastic deformation of a thermoplastic filament which is wound around two bolts which are movable relative to one another. The amount of energy that can be absorbed can be adapted by varying the number of windings: if more filament windings are provided, the cross-sectional area of the energy-absorbing material, and thus the amount of energy that can be absorbed, are increased; if fewer filament windings are provided, it is by contrast the case that the cross-sectional area of the energy-absorbing material, and thus the amount of energy that can be absorbed, are reduced.
Even though the device known from U.S. Pat. No. 3,694,019 A permits an adjustment of the amount of energy that can be absorbed, multiple disadvantages remain evident. For example, the production of the filament windings has proven to be particularly cumbersome. Furthermore, the use of plastics as energy-absorbing material has the disadvantage, in relation to metals, of lower thermal and mechanical resistance to environmental influences such as heat, cold and vibrations, which are inevitably encountered in vehicles.
A durable and nevertheless easily exchangeable device is desirable in which the amount of energy that can be absorbed in the event of a collision can be easily adjusted.